Atrial fibrillation (AF) is the most common arrhythmia in the perioperative period. Previously considered a benign and self-limited entity, recent data suggest that perioperative AF is associated with considerable morbidity and mortality and may predict long-term AF and stroke risk in some patients. Despite known risk factors, AF remains largely unpredictable, especially after noncardiac surgery. As a consequence, strategies to minimize perioperative risk are mostly supportive and include avoiding potential arrhythmogenic triggers and proactively treating patient- and surgery-related factors that might precipitate AF. In addition to managing AF itself, clinicians must also address the hemodynamic perturbations that result from AF to prevent end-organ dysfunction. This review will discuss current evidence with respect to causes, risk factors, and outcomes of patients with AF, and address current controversies in the perioperative setting.